Tri-allelic pattern at the TPOX locus: a familial study.

Area of Science:

• Genetics
• Forensic Science
• Human Population Genetics

Background:

• The TPOX short tandem repeat (STR) locus exhibits a variable number of AATG repeats, with tri-allelic genotypes being rare but more prevalent in specific populations.
• Accurate characterization of the TPOX third allele remains limited, hindering a comprehensive understanding of its genetic basis and inheritance patterns.

Purpose of the Study:

• To investigate the nature of the TPOX third allele in a large pedigree exhibiting tri-allelic genotypes.
• To determine the inheritance pattern and potential chromosomal linkage of the TPOX extra allele.

Main Methods:

• Analysis of 45 individuals from a single pedigree with documented tri-allelic TPOX genotypes.
• Karyotype analysis to rule out chromosomal abnormalities.
• Pedigree analysis to trace the inheritance of the TPOX third allele.

Main Results:

• Six tri-allelic cases (genotype 8-10-11) were identified, all in female subjects, consistent with a Type 2 tri-allelic pattern (three copies of the TPOX STR sequence).
• Pedigree analysis suggested that allele 10 represents the TPOX third allele, located distant from the main TPOX locus.
• Evidence indicated a potential linkage of the TPOX extra-allele-10 with the Xq chromosome.

Conclusions:

• This study provides the first large pedigree analysis to elucidate the TPOX tri-allelic pattern.
• The findings suggest that the TPOX third allele (allele 10) is inherited independently and may be linked to the Xq chromosome.